Rue du chat qui pêche (Street of the cat which goes fishing) - supposedly the narrowest street in Paris. Still nothing compared to the streets in Vietnam though.
Legend has it that an alchemist used a black cat for his practice of the art, but some students killed and threw it into the Seine for fear of his magic. Yet from time to time, people still see a black cat quietly goes fishing on the edge of the Seine (L’histoire des rues de Paris).
Near the end of this street is a road leading to the best tavern jazz bar in La Quartier Latin. My lungs die a little just thinking of the amount of cigarette smoke they inhaled there.

Yeah, graffiti art is very big in Paris @somnia but most of the time, they get erased right after they're painted on the wall because Parisian council has a rule against defacing the old Paris' bricks and stones.